The invention relates generally to prepaid smart cards for the delivery of goods/services, and to the use of such prepaid smart cards with subscriber identity modules, and which, for example, may find particular application in cellular or wireless telephone networks.
The invention is a method and apparatus and will be described as applied to a cellular or wireless telephone and network of the GSM type. It should be understood however that the invention is not limited to such GSM cellular wireless network nor to telephones, but may find application elsewhere, wherever there is provision of services and/or goods which are paid for with prepaid smart cards.
Smart cards or electronic chip cards are usually the size of a conventional credit card and have six or eight electrical contacts on one face and include inside an integrated circuit with memory and may include a microprocessor. Data and programs for manipulating the data and communicating outside the card are included in the integrated circuit. In the past the prepaid cards have been widely used in the purchase of telephone service, particularly in France and Germany, where public pay telephones accept the cards instead of coins typically the cards are purchased at the post office for a specific amount. The cards are inserted in a public pay telephone, connection is made to the contacts and units of value are removed from the card as the telephone call progresses. The mechanical and electrical specifications of the cards is standardized and one set of standards is published by the ANSI (American National Standards Institute), 11 West 42 Street, New York, N.Y. 10036 under the title xe2x80x9cIdentification cards-Integrated circuit(s) cards with contactsxe2x80x9d ISO 7816-1 and ISO 7816-2.
Smart cards have been manufactured and are commercially available from several companies including those of applicant""s assignee, GEMPLUS Card International, Avenue du Pic de Bertagne, Parc d""activitxc3xa9s de la Plaine de Jouques, 13420 Gemenos, France.
Cellular wireless networks are widely spread across the globe today. These networks are built to one of a few technical standards, which are GSM, DCS 1800, and PCS 1900. The present invention is described with reference to GSM but is not limited to GSM. The standards on wireless networks may be obtained from ANSI. Particulary attention is directed to standard ETSI/GSM 11.11. Those wishing additional information on cellular wireless telephone and operation are referred to a number of books in the field, for example Mouly, Michel and Pautet, Marie-Bernadette, The GSM System of Mobile Communications, 1993, Loissoy-les-Chateaux, France, Europe Media Duplication S. A.; or Clayton, Michael, GSM Global System for Mobile Communications North Sidney, Australia, Security Domain Pty Limited.
These cellular technologies today have some of the latest techniques. In most cellular wireless networks there is a subscriber identity module, SIM, which is in the handset. It identifies the subscription to the cellular wireless network. In some cellular telephones, the SIM is permanently installed in the telephone, but in more modern equipment it is removable and is mounted in a smart card.
The advantage of a removable SIM mounted in a smart card is that a subscriber may carry his SIM with him and insert it in any cellular telephone which will accept the smart card. This permits him both to use the card and to be billed on his home number.
In order to subscribe, one needs to pass a credit check. As a result, only credit worthy people can get wireless service. The networks do not address the market segment of xe2x80x9ccredit challengedxe2x80x9d people who cannot prove that they are reliable enough to be treated as a regular subscriber.
GSM based networks rely on a subscriber number called an International Mobile Subscriber Identity, IMSI, that is to be attached to an individual. Thus, anonymous subscribers cannot be offered services since they need to be identified first, and then attached to a unique IMSI. In GSM based networks, the IMSI number is stored in the SIM card. When inserted into the handset, the SIM provides to the network information about the subscriber that is necessary for establishing a call and for billing the call.
Because of this arrangement those potential customers who cannot qualify as subscribers and do not get any service. Based on today""s analog subscription rate, then 40%-50% of people applying for subscriptions have been denied credit and thus denied service.
Depending on the country and also depending on the distribution method in that country, the problem can get more serious. In Europe, for example, the subscription process occurs at the point of sale. If the credit check at the point of sale is negative, then the user will be refused service without having to purchase any goods. However, in North America an individual can buy a xe2x80x9cready to goxe2x80x9d package in many different consumer stores, such as Radio Shac or Wal Mart without having to sign any contract at the time of purchase. The subscription process is done over-the-air later, usually at home. Consequently, the potential user can spend a few hundred dollars, e.g. $200, for a package that he is not guaranteed to get any service from. This is a major problem that has not been solved to date.
There is definitely a need to address the market segment of the xe2x80x9ccredit challengedxe2x80x9d individuals in a different way than GSM can provide today. There have been several attempts to provide a xe2x80x9cprepaid typexe2x80x9d of service over GSM. But, none of them truly provides the solution expected by network operators. A first solution is to monitor units from the network, and to bill a prepaid card in the handset in real time. A second solution proposed is to use a service sometimes called xe2x80x9cAdvice of Chargexe2x80x9d, AOC, which is more fully defined by GSM 11.11. Both of these solutions have drawbacks. The first solution, prepayment managed from the network, is a viable alternative, but with shortcomings. It is very expensive for the network operator. It requires an Intelligent Networking infrastructure, IN, with Hot Billing, HB, capability, as well as a network capable of on-line tax or rate information. In this prepaid managed system, the user remains attached to a SIM card, must considered handled as a subscriber and has to be managed as such.
The second solution, AOC, provided by GSM was not intended for prepayment type of applications, but more for family usage or rental applications. In AOC, there is always a subscription attached to the account. The xe2x80x9cprepaid modexe2x80x9d is not seen from the billing, and is not reflected on the final bill. The subscriber can at any time turn his subscription into a restricted mode when he wants to lend his handset to someone. In this mode, the units are decremented in the card using a network based telephone schedule of charges until all units have been consumed. Although it can be assimilated to prepaid applications, it is never reflected on the subscriber""s bill if he remains overall a xe2x80x9ccredit worthy subscriberxe2x80x9d. Also, such implementation suffers from a lack of security, and is not intended for prepaid applications initially, and is believed to be subject to probable fraud.
All of the previous GSM systems require the user (or at least the purchaser of a cellular phone) to be identified. There is no such thing as an anonymous user of a cellular telephone. An object of the present invention is to provide a cellular telephone which may be used completely anonymously.
A further object of the invention is to provide a prepaid telephone service, which has enhanced security or, put another way, reduced opportunity for fraudulent use.
An object of the invention is to provide an apparatus, method and smart card which will provide a network of independent prepaid service based on a fixed tariff structure that will be offered to xe2x80x9ccredit challengedxe2x80x9d individuals in the form of a prepaid throw away smart card.
In an alternative embodiment, the smart card may be used continuously in that new prepayment value may be placed in the card. As of today, GSM defines a xe2x80x9cMobile Stationxe2x80x9d, MS, as having a xe2x80x9cMobile Equipmentxe2x80x9d, ME, and a xe2x80x9cSubscriber Identify Modulexe2x80x9d, SIM; MS=ME+SIM. Such a combination is mandatory for operating a service. According to an aspect of the invention, the SIM is no longer attached to a subscriber, but will be identified to the network operator as an anonymous prepaid type SIM. Prior to sale of the telephone, such a SIM would be programmed and inserted into the handset. It would be a SIM with restricted capabilities, e.g. 611 calls allowed only. If the purchaser wished to convert his SIM to a traditional subscription to a cellular phone, he could initiate the subscription process, OTA, and the SIM could be turned into a full subscription attached to a user after approval of the user""s credit check. In the case of the credit check being unsuccessful, or if the user wished, there would be another card in the package with the cellular telephone with an amount of units already loaded, to be inserted in an additional slot reserved for that purpose in the handset.
Because of that additional card, the user could still benefit from a wireless service without passing the credit check by using the additional card. Once the card was consumed, i.e., all of the units or value of the card had been used in calls, the user could buy another card to continue with the service. This provides the network operator with a secure financial position for such individuals, and provides the user of cellular service who intend to remain anonymous with the ability to do so. Thus a one-stop shopping solution is provided for the user who has good credit who wishes to retain traditional service, and for the user who is credit challenged, as well of the vendor of cellular equipment to users.
The concept and implementation as proposed herein opens the door to an untouched area of promotional campaigns wherein a third party could offer cellular air time by mailing prepaid cards as part of the marketing program. It turns the handset into a cellular prepaid phone.
According to an aspect of the invention, there is provided a method for enabling service from a wireless telephone having a SIM and a prepaid card in the telephone comprising the steps of calculating in the card a certificate as a function of (i) number of prepaid units remaining in the card, (ii) serial number in the card, and (iii) a key number in the card; and transferring from the card to the SIM (i) said number of prepaid units remaining in the card, and (ii) the card""s serial number; then calculating in the SIM a number which should be the same as the card key number based on said transferred number of prepaid units remaining in the card and said card serial number; and calculating in the SIM a certificate as a function of said transferred number of prepaid units remaining in the card and said calculated number which should be the same as said key number in the card; then comparing said calculated certificates from said card and from said SIM; and if coincident in said comparison, then enabling said telephone in said network.
According to a further aspect of the invention there is provided an apparatus which automatically performs the steps of the first described method.
According to another aspect of the invention, there is provided a modified prepaid secure smart card which in normal use in a network allows the transfer of goods/services to a user of the card from a network operator by subtracting prepaid units of value stored in said card in exchange for said goods/services. The card is a card-shaped carrier having a terminal, and an integrated circuit embedded in the carrier and connected to said terminal. The integrated circuit includes a serial number register for storing a serial number unique to each card; a prepaid units register for storing a number of units of prepaid value; a switch responsive to interrogation at the terminal to write to the terminal the serial number in the serial number register, and to write to the terminal the number of prepaid units remaining in said units register; a key number register storing a key number, which has a first portion unique for each card, and a second portion which is common to a plurality of cards, and which is unique for a network operator; an algorithm stored in said card, said algorithm in normal use of said card not being readable in said terminal, and a microprocessor for calculating a certificate in accordance with the algorithm as a function of the key number and the number in the prepaid register, and the certificate being readable at the terminal.
According to another aspect of the invention, there is provided an improved subscriber identification module, SIM, for operating with prepaid cards and with a network that provides goods/services via said network. The SIM includes an integrated circuit having an input for receiving from one prepaid card (i) a serial number of said card, (ii) a number of prepaid units remaining in the card, and (iii) a certificate compiled by said card from its serial number, card key number, an algorithm therein, and number of prepaid units remaining in the card; a diversification key which is the same for a plurality of modules of a network; first and second algorithms; a microprocessor for calculating (i) a card key number with the first algorithm as a function of the diversification key, and the receive serial number of the card, and where the calculated card key number should be the same as the key number in said card; and (ii) calculating a certificate with the second algorithm as a function of the calculated card key number, and the received number of prepaid units remaining in the card; and (iii) comparing the calculated certificate with said received certificate, and (iv) if coincidence, generating an enable signal whereby goods/services are provided in accordance with said generated enable signal.
According to a further object of the invention, there are provided integrated circuits of the types first described in the preceeding two paragraphs for use in prepaid smart cards, and for use in SIMs.
These and other objects and features of the invention will become more apparent from the preferred embodiments described with reference to the attached drawings, which are for the purposes of illustration and not limiting of the invention.